BEIRUT — Syria's most prominent defector offered himself up Thursday as a figure to unite the fractious opposition, saying he failed to persuade his former friend, President Bashar Assad, to end a bloody crackdown that has killed thousands of Syrians.

The remarks by Manaf Tlass, a Syrian brigadier general until he abandoned the regime this month, were published in a Saudi newspaper just as opposition factions gathered in Qatar to try to agree on a transitional leadership if Assad's regime falls.

Some opposition members are deeply skeptical of Tlass, believing he's far too close to the regime.

Mahmoud Othman, a member of the opposition Syrian National Council, said Tlass would simply "bring back the regime with a different image."

"Those who recently defected from the regime must not take part in leading the transitional period," Othman told The Associated Press from Istanbul, where he is based. "After the transitional period, the Syrian people will choose whomever they want through the ballots."

Members of the SNC met Thursday, but made no decisions on a possible leadership to fill the vacuum if Assad falls, according to Burhan Ghalioun, a former leader of the group.

The SNC has acted as the international face of the revolution, but it has been unable to unite all dozens of disparate rebel and opposition factions under one banner.

Ghalioun said talks would continue Friday and could stretch on past this series of meetings.

Tlass, a commander in the powerful Republican Guard and the son of a former defense minister, defected three weeks ago. Although the regime has remained largely intact over the course of the 17-month-old uprising, the pace of defections appears to be picking up.

"I will try to help as much as I can to unite all the honorable people inside and outside Syria to put together a roadmap to get us out of this crisis, whether there is a role for me or not," he told the Al-Sharq Al-Awsat daily in an interview.

He said he was in Saudi Arabia – a key financial backer of the rebellion – to assess what kind of assistance the oil-rich nation could give to help create a new Syria. He said he does not see a future for Syria with Assad at the helm. The last time he saw the president, he said, was about a year ago.

Turkey's Foreign Ministry also announced a surprise visit by Tlass on Thursday. He attended a dinner with Foreign Minister Ahmet Davutoglu, who has been an outspoken Assad critic. Turkey's intelligence chief and a senior foreign ministry official also were at the dinner.

Tlass left Davutoglu's residence after about an hour, wearing a dark suit with a light blue shirt, the top buttons undone. He didn't take any questions and was driven away in the back of a BMW.

Since his defection, Tlass has spoken publicly only twice, both times to Saudi-controlled media.

Tlass, once a personal friend of Assad, told the newspaper that the regime has many good people without blood on their hands and that the country's institutions should be preserved. He said he tried to persuade the president not to listen to his inner circle of security advisers who were all recommending a harsh crackdown on the uprising.

Tlass said he defected when he realized the regime could not be deterred from its single-minded pursuit of crushing the opposition.

"Sometimes in a friendship you advise a friend many times, and then you discover that you aren't having any impact, so you decide to distance yourself," he said.

A handsome man in his mid-40s, Manaf led an extravagant lifestyle, and he and his wife were fixtures on the social scene in Syria, where he often spoke on Assad's behalf.

Tlass was also a powerful Sunni in a government dominated by the Alawite sect, an offshoot of Shiite Islam. His father, Mustafa Tlass, was the most trusted lieutenant of the late Hafez Assad, the president's father and predecessor.

The conflict in Syria, which activists say has killed more than 19,000 people since March 2011, has drawn deep international condemnation. But world powers have few options to help beyond diplomacy – in part because of fears that any military intervention could exacerbate an already explosive battle. Syria's close ties to Iran and the Islamic militant group Hezbollah in Lebanon mean that the conflict has the potential to draw in the country's neighbors.

In Washington, the Obama administration is weighing its options for more direct involvement in the Syrian civil war if the rebels opposing the Assad regime can wrest enough control to create a safe haven for themselves, U.S. officials said.

Secretary of State Hillary Rodham Clinton says it's only a matter of time before the rebels have enough territory and organization to create such areas.

"More and more territory is being taken," Clinton said this week. "It will eventually result in a safe haven inside Syria, which will then provide a base for further actions by the opposition."

Still, U.S. officials are insisting they won't provide arms to Syria's anti-Assad forces or push for a no-fly zone over rebel-controlled areas.

For more than a week, Assad's regime has suffered a string of blows, although his forces are regaining their momentum. After a rebel rush on the capital – including a brazen bombing that killed four top regime insiders – the government routed the fighters by calling in attack helicopters and heavy weapons that devastated entire neighborhoods.

Rebels have been fighting for six days in the commercial capital Aleppo, and on Thursday they braced for a government onslaught amid reports that the regime is massing reinforcements to retake the embattled city of 3 million. They reported more intense firepower being used against them, including artillery strikes.

"Regime forces have been randomly shelling neighborhoods, and the civilians are terrified," local activist Mohammed Saeed told the AP via Skype.

U.S. State Department spokeswoman Victoria Nuland said Washington has "grave concerns" about tanks and fighter jets being used in a densely populated city.

"The concern is that we will see a massacre in Aleppo, and that's what the regime appears to be lining up for," she said.

The clashes have spread to neighborhoods close to the center of the city, which has a medieval center that is a UNESCO world heritage site.

According to the Britain-based Syrian Observatory for Human Rights, some 130 people have been killed in Aleppo since the clashes there began last Saturday.

As the violence continues, U.N. Secretary General Ban Ki-moon said he fears for Syria's future. On Thursday, he paid his respects to the 8,000 victims of the 1995 Srebrenica massacre – and said he does not want his successor to have to do the same 20 years from now in Syria.

"The international community must be united not to see any further bloodshed in Syria because I do not want to see any of my successors, after 20 years, visiting Syria, apologizing for what we could have done now to protect the civilians in Syria – which we are not doing now," he said during a visit to a memorial-cemetery complex near Srebrenica, Bosnia-Herzegovina.

live blog

Hussein Ali Omar, 60, one of 11 Lebanese Shiite pilgrims that Syrian rebels have been holding for three months in Syria, hugs his mother, right, upon arrival at his house in the southern suburb of Beirut, Lebanon, 2012. Syrian rebels freed Omar on Saturday in a move aimed at easing cross-border tensions after a wave of abductions of Syrian citizens in Lebanon. The Shiite pilgrims were abducted May 22 after crossing into Syria from Turkey on their way to Lebanon. (AP Photo/Hussein Malla)

This image made from video and released by Shaam News Network and accessed Thursday, Aug. 23, 2012, purports to show the funeral of children in Daraya, near Damascus, Syria. Syrian troops backed by tanks and helicopters broke into a Damascus suburb on Thursday following two days of shelling and intense clashes as part of a widening offensive by President Bashar Assad's forces to seize control of parts of the capital and surrounding areas from rebel fighters, activists said. At least 15 people were killed in the offensive on Daraya, only a few miles (kilometers) southwest of Damascus. (AP Photo/Shaam News Network SNN via AP video)

Clashes between Assad supporters and opponents of the Syrian regime killed two people in Lebanon on Friday, the Associated Press reports. 17 people were injured.

The AP gives more context:

Syria was in virtual control of its smaller neighbor for many years, posting tens of thousands of troops in Lebanon, before withdrawing under pressure in 2005. Even without soldiers on the ground, Syria remains influential, and its civil war has stirred longstanding tensions that have lain under Lebanon's surface.

A Sunni gunman fires a gun during clashes that erupted between pro and anti-Syrian regime gunmen in the northern port city of Tripoli, Lebanon, Friday, Aug. 24, 2012. The latest round of fighting first erupted on Monday in northern Lebanon and at least 15 have been killed in Tripoli this week and more than 100 have been wounded in fighting that is a spillover from Syria's civil war. (AP Photo/Hussein Malla)

Syrian boy Musataf Alhafiz, 11, who fled his home with his family due to fighting between the Syrian army and the rebels, carries his brother Saif, 9 months, while he and others take refuge at the Bab Al-Salameh border crossing, in hopes of entering one of the refugee camps in Turkey, near the Syrian town of Azaz, Thursday, Aug. 23, 2012. Thousands of Syrians who have been displaced by the country's civil war are struggling to find safe shelter while shelling and airstrikes by government forces continue. (AP Photo/Muhammed Muheisen)

Lebanese commandos ride in an armored personnel carrier in preparation to enter the area of clashes between supporters and opponents of the Syrian regime, in the northern port city of Tripoli, Lebanon, Wednesday, Aug. 22, 2012. The civil war in Syria is affecting its fragile, tiny neighbor Lebanon in countless ways and has already spilled over into sectarian street clashes, kidnappings and general government paralysis.(AP Photo/Hussein Malla)

Activists say that Syrian security forces swept through two districts in Damascus on Wednesday, killing at least 31 suspected opposition fighters. The Associated Press reports that the army may have been targeting rebel teams that had been using the Nahr Eishah and Kfar Soussa neighborhoods to shell a nearby military airport.